1. Field of the Invention
The present invention relates to making yarns of aramid fibers having particulate material embedded in the surface of the individual fibers.
2. Description of the Prior Art
U.S. Pat. No. 3,823,035 issued Jul. 9, 1974 on the application of Sanders, discloses suffusing carbon black particles into the surface of nylon monofilaments by dissolving nylon at the surface of the monofilament and contacting the dissolved nylon with the carbon black.
U.S. Pat. No. 4,985,046 issued Jan. 15, 1991 on the application of Hartzler discloses treating the surface of aramid fibers with concentrated sulfuric acid to make the fibers more receptive to dyes and dye-promoting agents.
U.S. Pat. No. 4,525,384 issued Jun. 25, 1985 on the application of Aoki et al. discloses a process for heat treating yarns of aromatic polyamide filaments which avoid interfilament adhesion by sticking particulate spacer material to the surface of the fibers by a coating process with an aqueous dispersion.